1. Field of the Invention
The present invention relates to a form factor disk such as an optical or magnetic disk for use in electronic appliances, information appliances and so forth, and more particularly, to an ultra-small form factor disk including a metal hub capable of minimizing a thickness of the disk and simplifying a manufacture process.
2. Discussion of Related Art
As information technology advances, the performance of electronic appliances or information appliances has been rapidly improved, and high integration density for miniaturization has been also rapidly performed. In addition, a typical information storage medium such as a form factor disk has been rapidly minimized and slimmed. As a result, a detachable disk also has been rapidly developed in order to increase user's convenience and effective information transmission.
In general, the form factor disk such as an optical or magnetic disk includes a circular plate 1 made of a polycarbonate material and having a hole 2 at its center as shown in FIG. 1, and upper/lower metal hubs 3 located at upper and lower parts of the circular plate 1 and having a hole 4 aligned with the hole 2 as shown FIG. 2 (see U.S. Patent Application Publication No. 2003/0157292, published on Aug. 21, 2003).
The metal hubs 3 are attached to a magnetic rotational disk (a magnetic chuck) with a rotational shaft of the information appliances being inserted through the holes 2 and 4, and information is stored in an information storage region 5 of the circular plate 1 or the information stored in the information storage region 5 is read out, with the circular plate 1 being rapidly rotated about the rotational shaft depending on rotation of the magnetic rotational disk connected to a spindle motor.
As shown in FIG. 3, the upper and lower metal hubs 3a and 3b are located at the upper and lower parts of the circular plate 1 such that the holes 4 of the upper and lower metal hubs 3a and 3b are aligned with the hole 2 of the circular plate 1, and intermediate layers 6 made of a buffer material (polycarbonate) are inserted between the circular plate 1 and the hubs 3a and 3b. 
The process of adhering the metal hubs 3 to the circular plate 1 is a process having the highest degree of difficulty in manufacture of the form factor disk. However, the following problems may be encountered when the disk is manufactured through the conventional method.
First, since the intermediate layers 6 and the metal hubs 3 are layered on the upper and lower parts of the circular plate 1, a center thickness of the disk is increased. When the thickness of the disk becomes larger, since a height of the rotational shaft of the information appliances should be also increased to rotate the disk to make the information appliance thicker, it is difficult to make the appliances ultra-small and ultra-slim.
Second, since the metal hubs 3 are attached to the circular plate 1 through various processes, the productivity is lowered and the manufacturing cost increases. That is, after attaching the intermediate layers 6 between the upper and lower metal hubs 3a and 3b, adhesive epoxy is applied to the intermediate layers 6. Then, the upper and lower metal hubs 3a and 3b are respectively aligned with and attached to the upper and lower part of the circular plate 1. Therefore, a large number of manufacturing processes and difficulties due to the position alignment lower the productivity and increase the manufacturing cost.